A proposal to investigate the application of the techniques known as computerized axial tomography (CAT) or transaxial tomography to nuclear medical imaging to yield three-dimensional, quantitatively accurate images of radionuclide spatial distributions. We and others have demonstrated that a wide variety of techniques for CAT can be applied to emission (i.e. radionuclide) tomography. It has been shown that the noniterative techniques based on Fourier mathematics can easily be implemented on the minicomputer found in many nuclear medicine laboratories and that they have a significant advantage over iterative algorithms in speed. The primary aims of this continuing research are to improve and implement techniques for attenuation correction which can be used with the noniterative reconstruction techniques and to develop a system based upon the Anger gamma camera to permit clinical application of these techniques.